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2020


Transient coarsening and the motility of optically heated Janus colloids in a binary liquid mixture
Transient coarsening and the motility of optically heated Janus colloids in a binary liquid mixture

Gomez-Solano, J., Roy, S., Araki, T., Dietrich, S., Maciolek, A.

Soft Matter, 16, pages: 8359-8371, Royal Society of Chemistry, August 2020 (article)

Abstract
A gold-capped Janus particle suspended in a near-critical binary liquid mixture can self-propel under illumination. We have immobilized such a particle in a narrow channel and carried out a combined experimental and theoretical study of the non-equilibrium dynamics of a binary solvent around it – lasting from the very moment of switching illumination on until the steady state is reached. In the theoretical study we use both a purely diffusive and a hydrodynamic model, which we solve numerically. Our results demonstrate a remarkable complexity of the time evolution of the concentration field around the colloid. This evolution is governed by the combined effects of the temperature gradient and the wettability, and crucially depends on whether the colloid is free to move or is trapped. For the trapped colloid, all approaches indicate that the early time dynamics is purely diffusive and characterized by composition layers travelling with constant speed from the surface of the colloid into the bulk of the solvent. Subsequently, hydrodynamic effects set in. Anomalously large nonequilibrium fluctuations, which result from the temperature gradient and the vicinity of the critical point of the binary liquid mixture, give rise to strong concentration fluctuations in the solvent and to permanently changing coarsening patterns not observed for a mobile particle. The early time dynamics around initially still Janus colloids produces a force which is able to set the Janus colloid into motion. The propulsion due to this transient dynamics is in the direction opposite to that observed after the steady state is attained.

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link (url) DOI [BibTex]

2020


link (url) DOI [BibTex]


Interface-mediated spontaneous symmetry breaking and mutual communication between drops containing chemically active particles
Interface-mediated spontaneous symmetry breaking and mutual communication between drops containing chemically active particles

Singh, D., Domínguez, A., Choudhury, U., Kottapalli, S., Popescu, M., Dietrich, S., Fischer, P.

Nature Communications, 11(2210), May 2020 (article)

Abstract
Symmetry breaking and the emergence of self-organized patterns is the hallmark of com- plexity. Here, we demonstrate that a sessile drop, containing titania powder particles with negligible self-propulsion, exhibits a transition to collective motion leading to self-organized flow patterns. This phenomenology emerges through a novel mechanism involving the interplay between the chemical activity of the photocatalytic particles, which induces Mar- angoni stresses at the liquid–liquid interface, and the geometrical confinement provided by the drop. The response of the interface to the chemical activity of the particles is the source of a significantly amplified hydrodynamic flow within the drop, which moves the particles. Furthermore, in ensembles of such active drops long-ranged ordering of the flow patterns within the drops is observed. We show that the ordering is dictated by a chemical com- munication between drops, i.e., an alignment of the flow patterns is induced by the gradients of the chemicals emanating from the active particles, rather than by hydrodynamic interactions.

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link (url) DOI [BibTex]


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Automatic Discovery of Interpretable Planning Strategies

Skirzyński, J., Becker, F., Lieder, F.

Machine Learning Journal, May 2020 (article) Submitted

Abstract
When making decisions, people often overlook critical information or are overly swayed by irrelevant information. A common approach to mitigate these biases is to provide decisionmakers, especially professionals such as medical doctors, with decision aids, such as decision trees and flowcharts. Designing effective decision aids is a difficult problem. We propose that recently developed reinforcement learning methods for discovering clever heuristics for good decision-making can be partially leveraged to assist human experts in this design process. One of the biggest remaining obstacles to leveraging the aforementioned methods for improving human decision-making is that the policies they learn are opaque to people. To solve this problem, we introduce AI-Interpret: a general method for transforming idiosyncratic policies into simple and interpretable descriptions. Our algorithm combines recent advances in imitation learning and program induction with a new clustering method for identifying a large subset of demonstrations that can be accurately described by a simple, high-performing decision rule. We evaluate our new AI-Interpret algorithm and employ it to translate information-acquisition policies discovered through metalevel reinforcement learning. The results of three large behavioral experiments showed that the provision of decision rules as flowcharts significantly improved people’s planning strategies and decisions across three different classes of sequential decision problems. Furthermore, a series of ablation studies confirmed that our AI-Interpret algorithm was critical to the discovery of interpretable decision rules and that it is ready to be applied to other reinforcement learning problems. We conclude that the methods and findings presented in this article are an important step towards leveraging automatic strategy discovery to improve human decision-making.

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Automatic Discovery of Interpretable Planning Strategies The code for our algorithm and the experiments is available Project Page [BibTex]


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Advancing Rational Analysis to the Algorithmic Level

Lieder, F., Griffiths, T. L.

Behavioral and Brain Sciences, 43, E27, March 2020 (article)

Abstract
The commentaries raised questions about normativity, human rationality, cognitive architectures, cognitive constraints, and the scope or resource rational analysis (RRA). We respond to these questions and clarify that RRA is a methodological advance that extends the scope of rational modeling to understanding cognitive processes, why they differ between people, why they change over time, and how they could be improved.

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Advancing rational analysis to the algorithmic level DOI [BibTex]

Advancing rational analysis to the algorithmic level DOI [BibTex]


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Learning to Overexert Cognitive Control in a Stroop Task

Bustamante, L., Lieder, F., Musslick, S., Shenhav, A., Cohen, J.

Febuary 2020, Laura Bustamante and Falk Lieder contributed equally to this publication. (article) In revision

Abstract
How do people learn when to allocate how much cognitive control to which task? According to the Learned Value of Control (LVOC) model, people learn to predict the value of alternative control allocations from features of a given situation. This suggests that people may generalize the value of control learned in one situation to other situations with shared features, even when the demands for cognitive control are different. This makes the intriguing prediction that what a person learned in one setting could, under some circumstances, cause them to misestimate the need for, and potentially over-exert control in another setting, even if this harms their performance. To test this prediction, we had participants perform a novel variant of the Stroop task in which, on each trial, they could choose to either name the color (more control-demanding) or read the word (more automatic). However only one of these tasks was rewarded, it changed from trial to trial, and could be predicted by one or more of the stimulus features (the color and/or the word). Participants first learned colors that predicted the rewarded task. Then they learned words that predicted the rewarded task. In the third part of the experiment, we tested how these learned feature associations transferred to novel stimuli with some overlapping features. The stimulus-task-reward associations were designed so that for certain combinations of stimuli the transfer of learned feature associations would incorrectly predict that more highly rewarded task would be color naming, which would require the exertion of control, even though the actually rewarded task was word reading and therefore did not require the engagement of control. Our results demonstrated that participants over-exerted control for these stimuli, providing support for the feature-based learning mechanism described by the LVOC model.

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Learning to Overexert Cognitive Control in a Stroop Task DOI [BibTex]

Learning to Overexert Cognitive Control in a Stroop Task DOI [BibTex]


Toward a Formal Theory of Proactivity
Toward a Formal Theory of Proactivity

Lieder, F., Iwama, G.

January 2020 (article) Submitted

Abstract
Beyond merely reacting to their environment and impulses, people have the remarkable capacity to proactively set and pursue their own goals. But the extent to which they leverage this capacity varies widely across people and situations. The goal of this article is to make the mechanisms and variability of proactivity more amenable to rigorous experiments and computational modeling. We proceed in three steps. First, we develop and validate a mathematically precise behavioral measure of proactivity and reactivity that can be applied across a wide range of experimental paradigms. Second, we propose a formal definition of proactivity and reactivity, and develop a computational model of proactivity in the AX Continuous Performance Task (AX-CPT). Third, we develop and test a computational-level theory of meta-control over proactivity in the AX-CPT that identifies three distinct meta-decision-making problems: intention setting, resolving response conflict between intentions and automaticity, and deciding whether to recall context and intentions into working memory. People's response frequencies in the AX-CPT were remarkably well captured by a mixture between the predictions of our models of proactive and reactive control. Empirical data from an experiment varying the incentives and contextual load of an AX-CPT confirmed the predictions of our meta-control model of individual differences in proactivity. Our results suggest that proactivity can be understood in terms of computational models of meta-control. Our model makes additional empirically testable predictions. Future work will extend our models from proactive control in the AX-CPT to proactive goal creation and goal pursuit in the real world.

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Toward a formal theory of proactivity DOI Project Page [BibTex]


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Axisymmetric spheroidal squirmers and self-diffusiophoretic particles

Pöhnl, R., Popescu, M. N., Uspal, W. E.

Journal of Physics: Condensed Matter, 32(16), IOP Publishing, Bristol, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Tracer diffusion on a crowded random Manhattan lattice

Mej\’\ia-Monasterio, C., Nechaev, S., Oshanin, G., Vasilyev, O.

New Journal of Physics, 22(3), IOP Publishing, Bristol, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Semi-Supervised Learning of Multi-Object 3D Scene Representations

Elich, C., Oswald, M. R., Pollefeys, M., Stueckler, J.

CoRR, abs/2010.04030, 2020 (article)

Abstract
Representing scenes at the granularity of objects is a prerequisite for scene understanding and decision making. We propose a novel approach for learning multi-object 3D scene representations from images. A recurrent encoder regresses a latent representation of 3D shapes, poses and texture of each object from an input RGB image. The 3D shapes are represented continuously in function-space as signed distance functions (SDF) which we efficiently pre-train from example shapes in a supervised way. By differentiable rendering we then train our model to decompose scenes self-supervised from RGB-D images. Our approach learns to decompose images into the constituent objects of the scene and to infer their shape, pose and texture from a single view. We evaluate the accuracy of our model in inferring the 3D scene layout and demonstrate its generative capabilities.

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link (url) [BibTex]

link (url) [BibTex]


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Wetting transitions on soft substrates

Napiorkowski, M., Schimmele, L., Dietrich, S.

{EPL}, 129(1), EDP Science, Les-Ulis, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Blessing and Curse: How a Supercapacitor Large Capacitance Causes its Slow Charging

Lian, C., Janssen, M., Liu, H., van Roij, R.

Physical Review Letters, 124(7), American Physical Society, Woodbury, N.Y., 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Interplay of quenching temperature and drift in Brownian dynamics

Khalilian, H., Nejad, M. R., Moghaddam, A. G., Rohwer, C. M.

EPL, 128(6), EDP Science, Les-Ulis, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Fractal-seaweeds type functionalization of graphene

Amsharov, K., Sharapa, D. I., Vasilyev, O. A., Martin, O., Hauke, F., Görling, A., Soni, H., Hirsch, A.

Carbon, 158, pages: 435-448, Elsevier, Amsterdam, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Effective pair interaction of patchy particles in critical fluids

Farahmand Bafi, N., Nowakowski, P., Dietrich, S.

The Journal of Chemical Physics, 152(11), American Institute of Physics, Woodbury, N.Y., 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Visual-Inertial Mapping with Non-Linear Factor Recovery

Usenko, V., Demmel, N., Schubert, D., Stückler, J., Cremers, D.

IEEE Robotics and Automation Letters (RA-L), 5, 2020, accepted for presentation at IEEE International Conference on Robotics and Automation (ICRA) 2020, to appear, arXiv:1904.06504 (article)

Abstract
Cameras and inertial measurement units are complementary sensors for ego-motion estimation and environment mapping. Their combination makes visual-inertial odometry (VIO) systems more accurate and robust. For globally consistent mapping, however, combining visual and inertial information is not straightforward. To estimate the motion and geometry with a set of images large baselines are required. Because of that, most systems operate on keyframes that have large time intervals between each other. Inertial data on the other hand quickly degrades with the duration of the intervals and after several seconds of integration, it typically contains only little useful information. In this paper, we propose to extract relevant information for visual-inertial mapping from visual-inertial odometry using non-linear factor recovery. We reconstruct a set of non-linear factors that make an optimal approximation of the information on the trajectory accumulated by VIO. To obtain a globally consistent map we combine these factors with loop-closing constraints using bundle adjustment. The VIO factors make the roll and pitch angles of the global map observable, and improve the robustness and the accuracy of the mapping. In experiments on a public benchmark, we demonstrate superior performance of our method over the state-of-the-art approaches.

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[BibTex]

[BibTex]


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Cassie-Wenzel transition of a binary liquid mixture on a nanosculptured surface

Singh, S. L., Schimmele, L., Dietrich, S.

Physical Review E, 101(5), American Physical Society, Melville, NY, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Energy storage in steady states under cyclic local energy input

Zhang, Y., Holyst, R., Maciolek, A.

Physical Review E, 101(1), American Physical Society, Melville, NY, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Numerical simulations of self-diffusiophoretic colloids at fluid interfaces

Peter, T., Malgaretti, P., Rivas, N., Scagliarini, A., Harting, J., Dietrich, S.

Soft Matter, 16(14):3536-3547, Royal Society of Chemistry, Cambridge, UK, 2020 (article)

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DOI [BibTex]

DOI [BibTex]

2012


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Structure and aggregation of colloids immersed in critical solvents

Mohry, T. F., Maciolek, A., Dietrich, S.

Journal of Chemical Physics, 136(22), 2012 (article)

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DOI [BibTex]

2012


DOI [BibTex]


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Ewald sum for hydrodynamic interactions with periodicity in two dimensions

Bleibel, J.

Journal of Physics A: Mathematical and Theoretical, 45(22), 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Patchy worm-like micelles: solution structure studied by small-angle neutron scattering

Rosenfeldt, S., Luedel, F., Schulreich, C., Hellweg, T., Radulescu, A., Schmelz, J., Schmalz, H., Harnau, L.

Physical Chemistry Chemical Physics, 14, pages: 12750-12756, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Time correlations and persistence probability of a Brownian particle in a shear flow

Chakraborty, D.

European Physical Journal B, 85(8), Springer-Verlag Heidelberg, Heidelberg, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Local theory for ions in binary liquid mixtures

Bier, M., Gambassi, A., Dietrich, S.

The Journal of Chemical Physics, 137(3), American Institute of Physics, Woodbury, N.Y., 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Effect of ions on confined near-critical binary aqueous mixture

Pousaneh, F., Ciach, A., Maciolek, A.

Soft Matter, 8(29):7567-7581, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Surface integration approach: a new technique for evaluating geometry dependent forces between objects of various geometry and a plate

Dantchev, D., Valchev, G.

Journal of Colloid and Interface Science, 372(1):148-163, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Stability of thin wetting films on chemically nanostructured surfaces

Checco, A., Ocko, B. M., Tasinkevych, M., Dietrich, S.

Physical Review Letters, 109(16), American Physical Society., Woodbury, N.Y., etc., 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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The structure of fluids with impurities

Bier, M., Harnau, L.

Zeitschrift f\"ur physikalische Chemie, 226(7-8):807-814, Akademische Verlagsgesellschaft, Frankfurt am Main, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Stepwise swelling of a thin film of lamellae-forming poly(styrene-b-butadiene) in cyclohexane vapor

Di, Zhenyu, Posselt, Dorthe, Smilgies, Detlef-M., Li, Ruipeng, Rauscher, Markus, Potemkin, Igor I., Papadakis, Christine M.

Macromolecules, 45(12):5185-5195, 2012 (article)

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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A close look at proteins: submolecular resolution of two- and three-dimensionally folded cytochrome c at surfaces

Deng, Z., Thontasen, N., Malinowski, N., Rinke, G., Harnau, L., Rauschenbach, S., Kern, K.

Nano Letters, 12, pages: 2452-2458, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Field-induced breakup of emulsion droplets stabilized by colloidal particles

Kim, E. G., Stratford, K., Clegg, P. S., Cates, M. E.

Physical Review E, 85(2), 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Precursor films in wetting phenomena

Popescu, M. N., Oshanin, G., Dietrich, S., Cazabat, A. M.

Journal of Physics: Condensed Matter, 24, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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First passages in bounded domains: When is the mean first passage time meaningful?

Mattos, Thiago G., Mejia-Monasterio, Carlos, Metzler, Ralf, Oshanin, Gleb

Physical Review E, 86(3), Published by the American Physical Society through the American Institute of Physics, Melville, NY, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Gelation, phase behavior, and dynamics of beta-lactoglobulin amyloid fibrils at varying concentrations and ionic strengths

Bolisetty, S., Harnau, L., Jung, J., Mezzenga, R.

Biomacromolecules, 13, pages: 3241-3252, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Interactions of distinct quadrupolar nematic colloids

Eskandari, Z., Silvestre, N. M., Tasinkevych, M., Telo da Gama, M. M.

Soft Matter, 8(39):10100-10106, Royal Society of Chemistry, Cambridge, UK, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Transport of cargo by catalytic Janus micro-motors

Baraban, L., Tasinkevych, M., Popescu, M. N., Sanchez, S., Dietrich, S., Schmidt, O. G.

Soft Matter, 8(1):48-52, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Mesoscopic analysis of Gibbs’criterion for sessile nanodroplets on trapezoidal substrates

Dutka, F., Napiorkowski, M., Dietrich, S.

Journal of Chemical Physics, 136(6), 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Complete wetting of elastically responsive substrates

Bernardino, N. R., Dietrich, S.

Physical Review E, 85(5), 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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GPU-accelerated simulation of colloidal suspensions with direct hydrodynamic interactions

Kopp, M., Höfling, F.

The European Physical Journal - Special Topics, 210(1):101-117, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Liquid crystal boojum-colloids

Tasinkevych, M., Silvestre, N. M., da Gama, M. M. Telo

New Journal of Physics, 14, Institute of Physics Pub., Bristol, UK, 2012 (article)

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DOI [BibTex]

DOI [BibTex]


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Crystalline inverted membrane grown on surfaces by electrospray ion beam deposition in vacuum

Rauschenbach, S., Rinke, G., Malinowski, N., Weitz, R., Dinnebier, R., Thontasen, N., Deng, Z., Lutz, T., Rollo, P., Costantini, G., Harnau, L., Kern, K.

Advanced Materials, 24, pages: 2761-2767, 2012 (article)

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DOI [BibTex]

DOI [BibTex]

2011


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Collective dynamics of colloids at fluid interfaces

Bleibel, J., Dominguez, A., Oettel, M., Dietrich, S.

European Physical Journal E, 34(11), 2011 (article)

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DOI [BibTex]

2011


DOI [BibTex]


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Anomalous transport of a tracer on percolating clusters

Spanner, M., Höfling, F., Schröder-Turk, G. E., Mecke, K., Franosch, T.

Journal of Physics: Condensed Matter, 23(23), 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Dynamics of colloids in confined geometries

Almenar, L., Rauscher, M.

Journal of Physics: Condensed Matter, 23(18), 2011 (article)

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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The structure and melting transition of two-dimensional colloidal alloys

Law, A. D., Horozov, T. S., Buzza, D. M. A.

Soft Matter, 7(19):8923-8931, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Second harmonic light scattering from spherical polyelectrolyte brushes

Schürer, B., Hoffmann, M., Wunderlich, S., Harnau, L., Peschel, U., Ballauff, M., Peukert, W.

Journal of Physical Chemistry C, 115, pages: 18302-18309, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Solvation forces in Ising films with long-range boundary fields: density-matrix renormalization-group study

Drzewinski, A., Maciolek, A., Barasinski, A.

Molecular Physics, 109(7-10):1133-1141, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Pulling and pushing a cargo with a catalytically active carrier

Popescu, M. N., Tasinkevych, M., Dietrich, S.

Europhysics Letters, 95(2), 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Critical Casimir forces for Ising films with variable boundary fields

Vasilyev, O., Maciolek, A., Dietrich, S.

Physical Review E, 84(4), 2011 (article)

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DOI [BibTex]


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Study of \pi\pi correlations at LHC and RHIC energies in pp collisions within the quark-gluon string model

Nilsson, M. S., Bravina, L. V., Zabrodin, E. E., Malinina, L. V., Bleibel, J.

Physical Review D, 84(5), 2011 (article)

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DOI [BibTex]

DOI [BibTex]